Due to polarization voltage, zero drift and other factors, a baseline of a signal acquired would exceed a dynamic range of the signal during signal collection. When displayed, the signal with a high-amplitude baseline might not be displayed within a display area, or only part of the signal could be displayed within the display area.
In order to observe the complete signal, the baseline should be restored. Because the baseline is a low-frequency signal, a baseline restoration method provided by prior art uses a high-pass filter to remove the baseline. The frequency of the baseline is generally low, so the cut-off frequency of the high-pass filter should be very low. However, the lower the cut-off frequency of the high-pass filter, the longer the time required for the baseline to restore to zero, which leads to the baseline spending a very long time to restore to zero and the requirement for use could not be met. As shown in FIG. 1, assuming that the amplitude of the baseline is 1, the time required for the baseline to restore to zero by a high-pass filter would be more than 20 seconds.